Adding a price and if you ship internationally would help in selling the walkman. Also think posting in the 2nd hand market area makes it more visible than in chat.
Think of one, start high and reduce it if it doesn't sell is the best strategy. Not having a price can scare customers away as many (myself included) can imagine you want a small fortune given the condition. Also as a sidenote, there's no need to quote previous posts. Instead of using the Reply button (which quotes automatically) type in the box below and press Post Reply instead.
You could look at current and completed listings on ebay to get an idea of typical condition and pricing.